Zoom Projection Lens Autofocus Across Variable Throw Ratios
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Solution Overview
Problem
Existing autofocus capabilities in projection devices are limited to lenses with a fixed throw ratio and cannot be applied to projection devices with adjustable zoom ratios, such as zoom projection lenses.
Innovation Solution
A projection device and method that includes a zoom projection lens, sensor, focus adjustment module, zoom-ratio adjustment module, and detection module, utilizing an autofocus transfer function to calculate focus adjustment parameters based on projection distance and lens group displacement, enabling automatic focusing at any zoom ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing autofocus methods (multi-point correction or single-point correction with fixed distance) are used, then focus adjustment can be achieved for fixed throw ratio lenses, but these methods cannot be applied to zoom projection lenses with adjustable zoom ratios
Solution Approach 1:
The patent introduces a detection module that detects lens group position parameters at different zoom ratios. The control unit uses these position parameters along with projection distance to calculate focus adjustment parameters through a transfer function. This approach adapts the autofocus system to work with variable zoom ratios by dynamically adjusting focus based on changing lens parameters rather than relying on fixed correction tables or curves.
Solution Approach 2:
The patent introduces a detection module as an intermediary component that measures lens group displacement and provides position information to the control unit. This intermediary enables the system to bridge the gap between zoom ratio changes and focus adjustment requirements, allowing the autofocus function to adapt to zoom projection lenses without requiring complete redesign of the focus control mechanism.
2Adaptability or versatility
If lens group position is adjusted to change zoom ratio, then projection image zoom capability is improved, but focus position changes causing focus degradation
Solution Approach 1:
The patent implements a feedback mechanism where the detection module continuously monitors lens group position during zoom ratio adjustments. The control unit receives this position feedback and uses it to calculate the appropriate focus adjustment parameter. This closed-loop feedback system ensures that focus remains accurate despite changes in lens group position caused by zoom ratio adjustments, preventing focus degradation.
Solution Approach 2:
The system performs preliminary detection of lens group position before calculating focus adjustment. By detecting the lens group position in advance and using it to pre-calculate the required focus adjustment, the system prepares the focus mechanism to compensate for zoom-induced focus shifts before they occur, maintaining focus accuracy throughout the zooming process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables automatic focusing capability in projection devices with adjustable zoom ratios, ensuring clear imaging at any supported zoom ratio within the effective projection distance, and allows for fine-tuning to correct focus issues due to assembly tolerances or external forces.
Implementation Method 1
a sensor, and is configured to sense a projection distance between the projection device and the projection surface
Implementation Method 2
a zoom projection lens, and is configured to project the image beam generated by the projection module to a projection surface to generate a projection image
Data Source
AI summary
A projection device and a projection correction method are provided. The projection device includes a projection module, a zoom projection lens, a sensor, a focus adjustment module, a zoom-ratio adjustment module, a detection module and a control unit. The zoom-ratio adjustment module adjusts a position of a lens group in the zoom projection lens to adjust a zoom ratio of a projection image generated by the zoom projection lens projecting an image beam generated by the projection module. The control unit uses an autofocus transfer function to calculate a focus adjustment parameter based on a corresponding detection value generated by the detection module detecting displacement of the lens group and a projection distance sensed by the sensor, and controls the focus adjustment module according to the focus adjustment parameter to adjust an imaging focal length of the zoom projection lens.